In copending patent applications, Ser. No. 768,259, filed Aug. 22, 1985, and Ser. No. 833,304, filed Feb. 26, 1986 assigned to the same assignee as the present application, there are described methods of forming hollow fiber reinforced structures. The methods include impregnating fiber material while utilizing an inflatible bladder. This present application utilizes many of the steps described in the copending applications, and involves an improvement in such methods.
The aforementioned applications involve so-called resin transfer molding (RTM). In these copending applications, resin is applied to fiber material disposed between upper and lower mold pieces, with an inflatible bladder occupying a hollow area of the structures being formed.
The above applications are directed to forming structures in the same plane. However, in some applications, it is desirable to have portions of structures in one plane integrally connected to portions of structures extending in different planes. For example, in an automobile space or sub-frame, lateral roof beams between the side frames are sometimes required. Such laterial beams and other elements generally extend laterally from the side frames and at right angles thereto. It is desirable that these extending elements or sections be integral with the side frames.